Field of the Invention
The present invention generally relates to a sealed compressor for use in an electric refrigerator-freezer for household use, a showcase, or the like. More particularly, the present invention relates to a suction muffler of the sealed compressor.
Description of the Related Art
In recent years, there has been an increasing demand for global environment conservation. In particular, there has been a strong demand for higher efficiency in refrigerators, other refrigeration cycle devices, or the like.
As a conventional sealed compressor of this type, there are known a configuration in which a suction pipe communicating inside and outside of a sealed container and a suction inlet of a suction muffler of a compressor communicate with each other by means of an auxiliary hood made of a flexible material (see e.g., Japanese Unexamined Patent Application Publication No. Sho. 63-500878)), and a configuration in which a suction pipe communicating inside and outside of a sealed container and a suction inlet of a suction muffler of a compressor are arranged to face each other (see e.g., Japanese Laid-Open Patent Application Publication No. 2010-084677).
Now, the above stated conventional sealed compressors will be described with reference to the drawings.
FIG. 18 is a longitudinal sectional view of the conventional sealed compressor disclosed in Japanese Unexamined Patent Application Publication No. Sho. 63-500878. FIG. 19 is a cross-sectional view of the sealed compressor of FIG. 18. FIG. 20 is an enlarged view of major components of the sealed compressor of FIG. 18.
Referring to FIGS. 18 to 20, this sealed compressor reserves refrigerator oil 3 in a bottom portion of a sealed container 1 and is filled with cooling medium gas 5. The sealed compressor has a compressor body 7 elastically supported on the sealed container 1 by a suspension spring 9.
The compressor body 7 includes an electric (electrically driven) element 11 and a compression element 13 positioned above the electric element 11. The electric element 11 includes a stator 15 and a rotor 17.
The compression element 13 includes a crankshaft 23 having a main shaft 21 and an eccentric shaft 19 which are secured to the rotor 17, a block 29 provided integrally with a cylinder 27 forming a compression chamber 25, a piston 31 which is slidable inside the cylinder 27, a valve plate 33 for closing the end surface of the cylinder 27, a suction valve (not shown) for opening and closing a suction hole (not shown) provided on the valve plate 33, and a coupling member 35 for coupling the eccentric shaft 19 to the piston 31.
A suction muffler 39 is retained and fastened by the valve plate 33 attached to the end surface of the cylinder 27 and a cylinder head 37 for closing the valve plate 33.
The suction muffler 39 includes a muffler body 41 forming a muffling space and molded using resin such as PBT (polybuthylene terephthalate), PP (polypropylene), or PPS (polyphenylene sulfide), an opening portion 43 provided on the muffler body 41, and a hood 45 made of a flexible material.
One end of the hood 45 is elastically secured to the opening portion 43 of the muffler body 41 only by its own elasticity, and the other end thereof is pressed to elastically contact the inner wall surface of the sealed container 1 and enclosing an opening portion of a suction pipe 47 inside the container 1. The suction pipe 47 is attached on the sealed container 1 to provide communication between inside and outside of the container 1.
FIG. 21 is an enlarged view of major components of the sealed compressor disclosed in Japanese Laid-Open Patent Application Publication No. 2010-084677.
Referring to FIG. 21, a suction muffler 50 includes a muffler body 55 forming a muffling space and molded using resin such as PBT, PPS, or LCP (liquid crystal polymer), an opening portion 51 provided on the muffler body 55, and a suction hood 52 made of a flexible material.
One end of the suction hood 52 is elastically secured to the opening portion 51 of the muffler body 51 only by its elasticity, and the other end thereof is disposed with a gap from the inner wall surface of a sealed container 54 such that the other end faces an opening portion of a suction pipe 53 inside the sealed container 54. The suction pipe 53 is attached on the sealed container 54 to provide communication between inside and outside of the sealed container 54.
The operation of each of the above configured conventional sealed compressors will now be described.
In the sealed compressor, a current is supplied to the stator 15 to generate a magnetic field, and thereby the rotor 17 secured to the main shaft 21 is rotated, which causes the crankshaft 23 to be rotated. The piston 31 reciprocatingly slides inside the cylinder 27 via the coupling member 35 rotatably attached to the eccentric shaft 19.
By the reciprocation movement of the piston 31, the cooling medium gas 5 is suctioned into and compressed in a compression chamber 25, and is discharged into the refrigeration cycle (not shown), which operation occurs repeatedly.
The cooling medium gas 5 supplied from the refrigeration cycle (not shown) in a suction step flows through the suction pipe 47, the hood 45, and then the suction muffler 39, and is introduced into the compression chamber 25 through a suction hole (not shown) communicating with the compression chamber 25 by opening a suction valve (not shown).
The suction muffler 39 is capable of reducing a noise generated by the intermittent suction of the cooling medium gas 5. In addition, the suction muffler 39 is made of the resin having a low heat conductivity, which suppresses the cooling medium gas 5 flowing through the suction muffler 39 from being heated.
However, in the sealed compressor disclosed in Japanese Unexamined Patent Application Publication No. Sho. 63-500878, the hood 45 and a fitting portion of the opening portion 43 of the suction muffler 39 are made of materials with different linear expansion coefficients. Therefore, strict dimension accuracy is required in a mounting portion (not shown) of the hood 45 and the fitting portion. In addition, typically, rubber is used as the flexible material forming the hood 45. Since the hood 45 is exposed all the time to the cooling medium gas 5 and the refrigerator oil 3 under a high temperature condition, the rubber swells or is deformed, and cannot maintain its original shape. This makes a fitting state unstable.
As another fastening structure, it can be easily conceived that the hood 45 is fastened to the opening portion 43, for example, by tightening the hood 45 to the opening portion 43 by an elastic spring member, or the like. This increases components in number, and makes an assembling work very difficult.
In the structure for connecting the hood 52 and the opening portion 51 together in the scaled compressor disclosed in Japanese Laid-Open Patent Application Publication No. 2010-084677, as shown in FIG. 21, there is a distance between the suction pipe 53 and the hood 52. Therefore, it is possible to prevent the cooling medium gas or the like discharged from the suction pipe 53 from being directly suctioned into the suction muffler 50. However, because of a small area of the hood 52, the cooling medium gas discharged from the suction pipe 53 cannot be suctioned into the suction muffler 50 efficiently, and a part of the cooling medium gas leaks into the sealed container 54 at a connecting portion.